From £17,852
Experienced extension builder ready to quote for your work. Mayfair Design is the best extension builder in W1J. No obligation free quotes and many...
From £17,524
Luxe Refurbs is an established extension buildering business in W1J. We come highly recommended and provide competitive quotes for your work.
From £17,540
We Love Build - Three Arches is an established extension buildering business in W1J. We come highly recommended and provide competitive quotes for ...
From £17,972
We are a Design and Build Company, based in London.We focus on super prime and luxury residential renovations in and around London and internationa...
From £17,604
Trusted and professional extension builder in W1J. Experienced in all extension buildering work and keeping within budget and on quote. The Maybria...
From £17,884
Experienced extension builder ready to quote for your work. Future Homes Design and Build is the best extension builder in W1J. No obligation free ...
From £17,756
Originally established in 1996 ELV8 has set the highest standards within the building industry, achieving success by winning numerous gold awards f...
From £17,596
Need to find an Extension Builder near you for all your extension buildering work?
Pillar Contractors Ltd provides a local, trusted extensi...
From £17,900
Starfish Properties is a trusted extension builder serving customers in W1J and the surrounding area. Contact us to today to get a competitive quot...
From £15,708
Here at London Design and Build, our team of architects, interior designers, structural engineers and contractors, offer a bespoke, turn-key servic...

Underpinning ranges from £15,708 (London Design And Build based in SW1A) to £17,972 (We Love Build based in W1J), but the final cost will depend on the method of underpinning used, how much of your foundations need underpinning and where you live.
Comparing extension builders estimates for underpinning gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
Get quotes to underpin your home in W1J by posting a job with HaMuch and we will send it to extension builders in W1J.
Whether you’re looking to extend your kitchen with a side return extension or you want to convert your basement into a liveable space, read our cost guides to get an idea of how much each project costs before getting a more accurate quote from our database of reliable tradespeople.

Underpin a building - £17,534

Two storey extension - £88,050

Build a timber frame extension - £26,034

Build a swimming pool - £81,034

Single storey extension - £55,672

Side return extension - £41,878

Install an RSJ - £2,234

Outbuilding - £10,034

Build a Mansard loft conversion - £52,034

Loft conversion - £34,065

Build a kitchen extension - £42,034

Hip to gable loft conversion - £42,034

Granny annexe - £87,034

Garden office - £10,034

Convert a Garage - £16,034

Garage - £18,534

Build a flat roof extension - £22,034

Build a dormer loft conversion - £42,034

Concrete foundations - £6,284

Convert a bungalow loft - £29,034

Convert a basement - £37,878